Minimally invasive surgeries (such as endoscopic surgery) are performed via portals through which a variety of elongated instruments may be passed to gain access to an internal surgical site. Cannulas are often inserted into portals to provide a convenient passageway through which the various instruments may pass. When cannulas are inserted through portals formed in walls of the body, it is desirable that the cannulas be provided with means for controlling the release of fluid (for example, irrigation fluid) within the body.
Because many arthroscopic procedures require the use of pressurized fluid to distend and irrigate the joint being operated upon, the cannula must provide a sealed passageway to enable instruments to be passed into and out of the cannula while maintaining a fluid seal to prevent squirting whether or not an instrument is in the cannula passageway. The sealing of such cannula passageways is usually accomplished by one or more membranes (dams) attached to the proximal end of the elongated cannula. Current arthroscopic cannulas experience fluid leakage when an instrument is placed through the membranes (dams) of the cannula. When the dams are broken, the pressure release allows the fluid to squirt out of the cannula and disrupt the surgery.
There is a need for a cannula that is used in minimally invasive procedures and that has increasing fluid sealing capabilities to prevent fluid from squirting from within the body when instruments are passing through the cannula. A cannula that allows the fluid to gently leak out (and not squirt) is also needed.